Conventionally, there is known a substrate processing apparatus equipped with a multiple number of processing units each configured to perform a preset substrate processing on a substrate such as a semiconductor wafer or a glass substrate.
With regard to a substrate transfer in such a substrate processing apparatus, there is proposed a technique of carrying a substrate into/out of the processing unit while suppressing a processed substrate from being adversely affected by a pre-processed substrate (see, for example, Patent Document 1). Further, there is proposed a technique in which multiple pads configured to support a substrate and configured to be movable up and down by a diaphragm pump are provided as one set and multiple sets are provided. With this technique, by changing elevation states of the multiple sets individually, the substrate before processed and the substrate after processed can be supported at different positions (see, for example, Patent Document 2).
Patent Document 1: Japanese Patent Laid-open Publication No. 2002-299405
Patent Document 2: Japanese Patent Laid-open Publication No. H08-107136
In the first aforementioned prior art, however, since a substrate is supported by being inclined between a multiple number of holders having multi-level support surfaces, a peripheral portion of the substrate come into contact with the holders. Thus, if there is a film or the like on the peripheral portion of the substrate, for example, there is a concern that the film is cut so that dust may be generated from the peripheral portion of the substrate. Further, in the second aforementioned prior art, it is not checked whether the pads are actually elevated into the required elevation state as a fluid is supplied or discharged by the diaphragm pump.